GINZBURG-LANDAU MODELIZATION OF SUPERCONDUCTING MULTILAYERS WITH PROXIMITY EFFECT

A phenomenological modelisation of superlattices made of alternating superconducting (S) and normal (N) layers coupled by proximity effect is presented. It is shown that the anisotropy of such superconductors is not a universal quantity but depends on external parameters such as temperature and applied magnetic fields. We also show that due to the destruction of the proximity effect in th N layers under high magnetic fields, the ratio H-c2(parallel to)/H-c2(perpendicular to) is generally different from the anisotropy measured at low fields.